We now know that the way we talk about race has no scientific validity. There is no genetic basis that corresponds with any particular group of people, no essentialist DNA for black people or white people or anyone. This is not a hippy ideal, it's a fact. There are genetic characteristics that associate with certain populations, but none of these is exclusive, nor correspond uniquely with any one group that might fit a racial epithet. Regional adaptations are real, but these tend to express difference within so-called races, not between them. Sickle-cell anaemia affects people of all skin colours because it has evolved where malaria is common. Tibetans are genetically adapted to high altitude, rendering Chinese residents of Beijing more similar to Europeans than their superficially similar neighbours. Tay-Sachs disease, once thought to be a "Jewish disease", is as common in French Canadians and Cajuns. And so it goes on.

Williams passed away on Feb. 20 in Pasadena, at the age of 86, enough time to be denied a rightful ride in the Rose Parade because of her race and decades later to see that wrong righted.

When officials discovered Williams was a light-complexioned African American, the float she was to ride was canceled. Her story finally publicized, Williams got her trip down Colorado Boulevard in the 2015 Rose Parade…